The invention relates to a method for operating a drivetrain of a motor vehicle with internal combustion engine, automatic transmission and at least one drive axle, wherein for saving fuel during driving operation a clutch, which belongs to the automatic transmission, is disengaged when the drive pedal or gas pedal is not actuated and subsequently the internal combustion engine is turned off.
The invention also relates to a control device and a motor vehicle.
From DE 10 2010 008 726 A1 a method for operating a drive system of a motor vehicle with automatic twin clutch transmission and hybrid drive with internal combustion engine and electric motor is known. DE 10 2010 008 726 A1 describes how to most comfortably but also dynamically restart the internal combustion engine during driving operation after the internal combustion engine has been turned off or shut down.
As a measure for saving fuel in motor vehicles, in particular those including an automatic twin clutch transmission, the internal combustion engine can be turned off during driving operation under certain circumstances, for example when the driver does not actuate the gas pedal (so-called free-wheeling engine-off function” or a so-called “Start-Stop-Sailing”). In the free-wheeling engine-off” operating mode the active drive clutch of the twin clutch transmission is first disengaged and subsequently the internal combustion engine is turned off, which represents a further development of the operating mode referred to as “sailing”, in which the clutch is released and the internal combustion engine transitions into the idling, as soon as the gas pedal is not actuated.
In the free-wheeling engine-off function the internal combustion engine has to be started and power transmission to a drive axle be established as soon as possible when the driver actuates the gas pedal again in order to quickly reestablish the forward drive. The invention is based on the object to provide possibilities how this can be accomplished.